Calling species 'invasive'—and culling them—isn't done lightly. But it matters to Australia's threatened species

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: It may sound abstract, but distinctions between "native," "introduced" or "invasive" species can often be life or death. Species considered invasive in Australia—such as European rabbits and feral pigs—are often culled, while most native animals are generally left alone.

Debate over these terms doesn't usually go mainstream. But this month was different. On Oct. 13, independent Sen.

David Pocock brought a motion in federal Parliament calling for a long-term plan to "protect Australia's landscapes and wildlife from invasive species." In response, Greens Sen. Mehreen Faruqi took aim at the term "invasive," saying: "There's no need for labeling introduced species as invasive in a way that blames animals for the man-made problems raised by this motion. Animals are not villains to be shot or obstacles to be poisoned to death." As an ecologist and conservation scientist, the debate spoke to me about how important it is to explain why "invasive" species are given this title, the damage they can do and why many need to be eradicated or their numbers greatly reduced.

If we stop trying to control some invasive species, we risk condemning even more native animals to extinction and worsening Australia's environmental decline. Conservationists and authorities commonly use four words—introduced, feral, invasive and pest—to describe species present in Australia. Definitions can differ and there is debate over their exact meaning.

But their broad meanings are clear: An introduced species has been moved by humans to areas outside its known natural historic range. This can be accidental (think black rats on ships) or intentional (deer species introduced for hunting). Native species—such as the superb lyrebird—can also be considered introduced when moved to new locations in the same country.

Feral: This term refers to introduced domesticated species that now have wild populations independent of people. Feral cats, goats, horses, pigeons, pigs and camels are common examples in Australia. Invasive: Invasives are introduced species whose presence is concerning, either due to their clear (typically negative) impact on ecosystems or their rapid spread after introduction.